Round-bobbin case for sewing machines



April 30, 1963 H. ADAM ROUND-BOBBIN CASE FOR SEWING MACHINES Filed Oct.10, 1960 2 Sheets-Shes April 30, 1963 H. ADAM 3,087,447

ROUND-BOBBIN CASE FOR SEWING MACHINES Filed Oct. 10, 1960 2 Sheets-Sheet2 United States Patent Ofitice Patented Apr. 36, 1953 ROUND-BGBBEN CASEFOR SEWENG MACHINES Hermann Adam, Bielefeld, Germany, assignor to Anker-Phoenix Nahmaschinen AG, Bielefeld, Germany, a

German corporation Filed (Pct. 1t 1960, Ser. No. 61,630 Claims priority,application Germany Get. 12, 1959 6 Claims. (Cl. 112-231) My inventionrelates to a round-bobbin case for sewing machines of the rotaryloop-taker (rotary hook) type and particularly to round-bobbin cases forring-shaped loop-takers having a horizontal axis of rotation.

In the known bobbin cases of this type, one of the stop lugs or fingersof the case which abuts against a stationary stop of the machinestructure for preventing the bobbin case from rotating while theloop-taker hook is in operation, is provided with an eye through whichthe yarn coming from the bobbin in the casing passes to the materialbeing sewed. Threading the yarn through the small eye is inconvenient asit requires some time and good eyesight of the seamstress.

In sewing machines of diiicrent kind, such as roundbobbin machines witha loop-taker hook oscillating about a vertical axis, it is known toprovide the bobbin case with a slot through which the yarn passes fromthe bobbin case with a slot through which the yarn passes from thebobbin to the sewing material, and which facilitates threading of theyarn when inserting a full bobbin. Such slots are also being provided insome machines of other types. Among these is a machine with a rotaryhook which performs two revolutions for each stitch, a bobbin casing anda carrier for the casing are telescopically joined with each other andreceived within a loop-taker member in which they are kept by a latchmember in the proper position. The carrier of the bobbin casing isprovided with stop means cooperating with stationary abutrnents of themachine base to prevent rotation of the carrier. A finger of the bobbinhousing enters between the lugs of the bobbin-case carrier, and thisfinger possesses a slot for guiding the yarn. The finger carries on itsouter side a guiding spring which, together with the upper portion ofthe slot, forms an upwardly open yarn guiding eye through which theunder thread can pass to the sewing material.

However, it is not readily possible to provide the holding finger with aguiding slot for the under thread in a bobbin casing for ring-shapedloop-taker hooks that rotate about a horizontal axis. This is becausethe under thread passes out of the eye in a radial direction and hencetransversely to the rotation axis of the loop-taker hook. Furthermore,the necessity for light-weight and the limited space available for thebobbin casing in such horizontal-axis ring-shaped loop-taker devicesmake it necessary to give the stop lug for the bobbin case a relativelysmall wall thickness in the direction transverse to the longitudinalaxis of the loop-taker member. This does not permit replacing theabove-mentioned known yarn-guiding eye by a slot extending in the samedirection.

It is an object of my invention to solve this problem and to devise around-bobbin case for rotary loop-taker devices of the horizontal-axistype, that facilitates threading the bobbin yarn through the casing,thus reducing the necessary threading time as well as the requirementsas .to skill or eyesight of the seamstress.

To this end, and in accordance with my invention, I

give the stop lug or finger of the bobbin case a generally hook-shapedesign so located that, when the casing is in operative position, thebight of the hook is at the top and the two legs of the hook extenddownwardly, one being integral with the bobbin case proper Whereas theother is somewhat spaced from the main body of the casing in order toform a generally V-shaped slot of which one portion extends up into thebight of the hook. The width or thickness of the material forming theV-shaped slot in such a device extends parallel to the rotation axis ofthe bobbin case.

The foregoing and further features of my invention will be more fullydescribed in the following with reference to the embodiment of a bobbincase according to the invention illustrated by way of example on theaccompanying drawings in which:

FIGS. 1, 2 and 3 show the bobbin case in plan view, top view and partlysectional side view respectively.

FiG. 4 is a vertical section on the center axis of FIG. 1 and also showsa bobbin inserted.

FIG. 5 is a perspective view from the rear of the casing and an insertedbobbin.

FIGS. 6 and 7 show the bobbin case in a view similar to FIG. 1, but inrespectively diiferent stages of an under thread being threaded into,and guided by, the slot in a hook-shaped lug of the casing.

FIGS. 8, 9 and 10 relate to the manufacture of the bobbin casing andshow the casing incomplete in plan view and two vertical sectionsrespectively.

FIGS. 11a, b, c jointly show an exploded perspective view of theloop-taker, bobbin-case and cover assembly.

The illustrated bobbin case 1 for a rotary loop-taker forms a circularflange 2 which, when the case is in operative position, is guided in aring-shaped guiding groove 31 (FIG. 4) of the rotating loop-taker (hook)body 32. In this position, the case 1 is prevented from rotatingrelative to the loop-taker, by means of a nose 33 of a ring-shaped cover35 (FIG. llc) fixed in the sewing machine structure. The nose 3-3 entersbetween holding lugs or fingers 3 and 4 of the case 1. The guidinggroove 31 of the loop-taker body 32 defines the position of the case 1with respect to all radial directions as well as relative to one axialdirection. In the other axial direction, the case is kept in properposition by a nose 33 of a ringshaped cover 35 (FIG. for the loop-taker32. The bobbin 5 is rotatable about a horizontal axis within the cupspace 7 of the case 1 FIGS. 4, 5).

When a new bobbin is being inserted into the case, the under thread 10coming from the bobbin is first passed through a slot 8 (FIG. 5) in thewall of the casing. From slot 8, the under thread is passed beneath atension spring 9 and is then pulled in axial direction through theportion 11 of a thread-supplying or V-shaped slot (FIG. 6). Thereafter,the seamstress moves the under thread in radial direction until it isplaced against the bottom 15 of a vertical slot portion 12. Whileinserting the bobbin case 1 into the loop-taker member 32, the underthread is slightly pulled upwardly by the seamstress. This causes thethread to pass from the bottom 15 of the threadguiding slot 12 up to athread-guiding edge 14 (FIG. 3) formed in the top portion of the slot12.

In order to prevent the thread, during the vertical upward displacementjust described, from being caught by the tip 16 (FIG. 6) formed by thegenerally V-shaped arrangement of the two slot portions 11 and 12, andfrom being thus inadvertently diverted back into the slot portion 11,the tip 16 is somewhat set back from the right-hand side of the slotportion 12. To prevent that the upper (needle) thread 17 (FIG. 1), whichduring loop or lock-stitch formation glides along the planar front face13 of the case upwardly, is not inadvertently caught by the tip 16, thetip is flush with the planar front face 13 of the case 1 and has roundededges.

For improved uniformity of the knots formed by upper thread and underthread in the sewing material, the bob bin 5 (FIGS. 4, 5) is journalledin the cup space 7 of the case 1 at the outer periphery of the bobbin.The slight friction at the periphery then prevents the bobbin fromperforming an undesired leading rotary travel relative to the case whenthe bobbin is full and hence has relatively great inertia, and has alsothe effect that during each cycle of stitch formation the bobbin isturned only a given desired amount. As a consequence, the pull of thethread during rotation of the bobbin remains sub stantially uniform.

The front side 13 of the case 1 is provided with a relatively largecentral opening 18. The resulting reduction in weight and inertia has afavorable effect upon the stitch knotting operation. To secure an easyand uniform pull-oif of the upper-thread loop 17 (FIG. 1) from thebobbin case 1, the transition radius 19 from the front face 13-to theconical portion 20 of the bobbin case is made so large that the centerpoint of the radius 19 is located substantially in the plane of theguiding edge 2 (FIG. 2).

It will be apparent from the foregoing that the stop lug 3 in a bobbincase according to the invention has generally the shape of an inverted Uwhose one leg is integral with the material of the casing wall 13 thatforms the bottom of the cup space, whereas the other leg of the U-shapeextends downwardly and terminates at some distance away from the wallstructure of the casing so as to form the above-mentioned slot portion11 which together with the space between the U-legs forms theabove-mentioned V-shaped slot. This slot extends toward the center axisof the bobbin case a sufficient distance to occupy part of the cup-spacebottom (FIG. 3). The guiding edge 14 in the bight of the U-shaped hookmember or lug 3 is inclined in an upward direction from the open side ofthe cup space toward the opposite side.

The case 1 can readily be produced from sheet metal by drawing, thisoperation being facilitated by the provision of the large opening 18.The manufacture is preferably such that first a cup 21 (FIG. 9) is drawnwhich is to constitute the front portion 13, the conical peripheralportion 20 and the guide-way portion 2 of the case. Thereafter a lug 22is cut and bent out of the cup structure 21 (FIGS. 8, 9), and theultimate stop lugs 3 and 4 are then machined or stamped out of thematerial at 22. The inner cylindrical portion 23 (FIG. of the casing isthereafter welded together with the outer cup structure 21 to form thecup space for receiving the bobbin 5. According to FIG. 8, the rightside 24 of the lug 22 is cut on a slant. As a result, the right handside 25 (FIG. 1) of the ultimate stop lug 4 possesses the same slantingshape. The inclination of this slant is such that, during stitchknotting operation, the upper (needle) thread 17 (FIG. 1) can be pulledoff the bobbin case along the inclined edge 25 of lug 4 withoutencountering resistance.

I claim:

1. Round-bobbin case for rotary loop-taker in sewing machines,comprising a generally cylindrical case structure having a cup spaceadapted to hold a bobbin for rotation about a horizontal axis when inoperation, two stop lugs extending upwardly away from said cup space andbeing peripherally spaced from each other to prevent rotation of saidstructure, one of said two lugs forming a hook of inverted U-shape whichhas its two U-legs extending from the U-bight downwardly, the one legremote fro-m said other lug being integral with said structure, theother leg terminating in spaced relation to said structure and formingtogether therewith a V-shaped slot, whereby the slot portion betweensaid two lugs permits threading of the bobbin yarn through the casingand the slot portion between the U-legs serves to guide the yarn fromthe bobbin to the sewing material.

2. Round-bobbin case for rotary loop-taker sewing machines, comprising agenerally cylindrical case structure having a cup space adapted to holda bobbin for rotation about a horizontal axis when in operation, twostop lugs extending upwardly away from said cup space and beingperipherally spaced from each other to prevent rotation of saidstructure, one of said two lugs forming a bight of inverted U-shapedwith a vertical threadguiding slot therebetween and which has its twoU-legs extending from the U-bight downwardly to for-m a slot portionbetween said U-legs for guiding the yarn from the bobbin to materialbeing sewed, the leg closest to the other of said two lugs terminatingin spaced relation to said structure and forming together therewith aV-sh-aped thread-insertion slot between the two lugs and joining saidvertical slot for permitting threading the bobbin yarn through said casestructure, said other lug being closely adjacent said V-shaped slot andshaped for deflecting an upper thread lo'op passing thereover away from"said V- shaped slot so as to prevent said thread loop from being caughtor severed in the latter, said case structure comprising :asubstantially frustoconical peripheral portion extending around said cupspace and having a circular edge for engaging the loop-taker, said twolugs and said peripheral portion consisting of a single integral pieceof material, and said lugs forming cut-outs of said peripheral portionand extending parallel to the plane of said cup .space.

3. Round-bobbin case for rotary loop-taker sewing machines, comprising agenerally cylindrical case structure having a cup space adapted to holda bobbin for rotation about a horizontal axis when in operation, twostop lugs extending upwardly away from said cup space and beingperipherally spaced from each other to prevent rotation of saidstructure, one of said two lugs forming a book of inverted U-shape whichhas its two U-legs extend from the U-bight downwardly, the one legremote from said other lug being integral with said structure, the otherleg terminating in spaced relation to said structure and formingtogether therewith a V-shaped slot, whereby the slot portion betweensaid two lugs permits threading of the bobbin yarn through the casingand the slot portion between the U-legs serves to guide the yarn fromthe bobbin to the sewing material, said V-shaped slot being in a radialplane relative to said axis and having a yamguiding surface extending insaid bight of said stop lug in 'a direction upwardly inclined from thecup side to the opposite side of the lug.

4. A round-bobbin case according to claim 2, said U-leg closest to saidother lug tapering in the direction of said insertion slot so as toenlarge the lower portion of said vertical slot at its juncture withsaid thread-insertion slot in the direction of the central axis of saidcase structure, said two lugs both being laterally set back toward saidcup space from the plane defined by the casing surface beneath said cupspace.

5. Round-bobbin case for rotary loop-taker sewing m-achines, comprisinga generally cylindrical case structure having a horizontal axis when inoperative position and forming a cup-shaped bobbin container for holdinga bobbin rotationally about said axis, stop lug means provided with athread-guiding slot lying in a plane perpendicular to said horizontalaxis, means forming a thread-supplying slot for introducing an upperthread and extending inwardly and inclined from the outer edge of saidcase structure to intersect said thread-guiding slot at an acute angle,said stop lug means further comprising a loopguiding member positionednear said thread-supplying slot and shaped to extend across a lineforming the extension of the axis of said thread-supplying slot forshielding the latter, said case structure forming a slitted outletopening spaced from said thread-supplying slot for passing a lowerthread downwardly from said bobbin, and

thread-tension regulating spring means arranged on said structurepartially covering said slitted outlet opening.

6. Bobbin case according to claim 5, said case structure including saidstop lug means and said thread-supplying and thread-guiding slots allconsisting of a single stamping and being integral with said bobbincontainer, and means forming a central opening in said case structurefor reducing the weight thereof.

References Cited in the file of this patent UNITED STATES PATENTSFlanagan May 8, 1906 Francis Dec. 2, 1919 Ayres Jan. 17, 1956 HowardSept. 18, 1956

1. ROUND-BOBBIN CASE FOR ROTARY LOOP-TAKER IN SEWING MACHINES,COMPRISING A GENERALLY CYLINDRICAL CASE STRUCTURE HAVING A CUP SPACEADAPTED TO HOLD A BOBBIN FOR ROTATION ABOUT A HORIZONTAL AXIS WHEN INOPERATION, TWO STOP LUGS EXTENDING UPWARDLY AWAY FROM SAID CUP SPACE ANDBEING PERIPHERALLY SPACED FROM EACH OTHER TO PREVENT ROTATION OF SAIDSTRUCTURE, ONE OF SAID TWO LUGS FORMING A HOOK OF INVERTED U-SHAPE WHICHHAS ITS TWO U-LEGS EXTENDING FROM THE U-BIGHT DOWNWARDLY, THE ONE LEGREMOTE FROM SAID OTHER LUG BEING INTEGRAL WITH SAID STRUCTURE, THE OTHERLEG TERMINATING IN SPACED RELATION TO SAID STRUCTURE AND FORMINGTOGETHER THEREWITH A V-SHAPED SLOT, WHEREBY THE SLOT PORTION BETWEENSAID TWO LUGS PERMITS THREADING OF THE BOBBIN YARN THROUGH THE CASINGAND THE SLOT PORTION BETWEEN THE U-LEGS SERVES TO GUIDE THE YARN FROMTHE BOBBIN TO THE SEWING MATERIAL.